Turning on `securehashesonly` seems to disable the `addurl` command:

```console
% git config --get annex.securehashesonly
true
% git annex addurl https://www.gutenberg.org/cache/epub/2591/pg2591-images.html
addurl https://www.gutenberg.org/cache/epub/2591/pg2591-images.html
  annex.securehashesonly blocked transfer of URL key
failed
addurl: 1 failed
% git annex addurl https://www.gutenberg.org/cache/epub/2591/pg2591-images.html --relaxed
addurl https://www.gutenberg.org/cache/epub/2591/pg2591-images.html (to www.gutenberg.org_cache_epub_2591_pg2591-images.html) ok
(recording state in git...)
% ls -l www.gutenberg.org_cache_epub_2591_pg2591-images.html
www.gutenberg.org_cache_epub_2591_pg2591-images.html -> .git/annex/objects/gg/kG/URL--https&c%%www.gutenberg.org%cache%epub%2591%pg2591-images.html/URL--https&c%%www.gutenberg.org%cache%epub%2591%pg2591-images.html

> [[fixed|done]] --[[Joey]]
